You will pay a premium for tires that are almost flat proof like the specialized armadillos($40 ea tire) and schwalbe marathon plus($45 ea tire). But if you don't want flats and don't want to repair them on the road, they are priceless. If you don't want to spend so much, a good compromise is Mr. Tuffy tire liners. They help a great deal. About $10-15 for a pair.